Fix target FILE_SET properties

Ensure custom rules are taken into account.

Source/cmTarget.cxx

@@ -2095,6 +2095,10 @@ cmBTStringRange cmTarget::GetFileSetsEntries(cm::string_view type) const
   if (cm::contains(this->impl->FileSetTypes, type)) {
     return cmMakeRange(this->impl->FileSetTypes.at(type).SelfEntries.Entries);
   }
+  auto strType = std::string{ type };
+  if (cm::contains(this->impl->FileSetRules, strType)) {
+    return cmMakeRange(this->impl->FileSetRules.at(strType).SelfEntries);
+  }
   return cmMakeRange(EmptyEntries);
 }
 
@@ -2105,6 +2109,10 @@ cmBTStringRange cmTarget::GetInterfaceFileSetsEntries(
     return cmMakeRange(
       this->impl->FileSetTypes.at(type).InterfaceEntries.Entries);
   }
+  auto strType = std::string{ type };
+  if (cm::contains(this->impl->FileSetRules, strType)) {
+    return cmMakeRange(this->impl->FileSetRules.at(strType).InterfaceEntries);
+  }
   return cmMakeRange(EmptyEntries);
 }
 
@@ -2944,6 +2952,12 @@ cmValue cmTarget::GetProperty(std::string const& prop) const
         types.push_back(fileSetType.first);
       }
     }
+    for (auto const& fileSetRule : this->impl->FileSetRules) {
+      if (!fileSetRule.second.SelfEntries.empty() ||
+          !fileSetRule.second.InterfaceEntries.empty()) {
+        types.push_back(fileSetRule.first);
+      }
+    }
     std::sort(types.begin(), types.end());
     fsTypes = types.to_string();
     return cmValue{ fsTypes };

Tests/RunCMake/target_sources/FileSetProperties.cmake

@@ -91,3 +91,13 @@ assert_prop_eq(lib1 FILE_SETS_HEADERS "a;b;HEADERS")
 assert_prop_eq(lib1 INTERFACE_FILE_SETS_HEADERS "a;c;d;HEADERS")
 assert_prop_eq(lib1 FILE_SETS_SOURCES "src1")
 assert_prop_eq(lib1 INTERFACE_FILE_SETS_SOURCES "src1")
+
+add_custom_rule(rule OUTPUT output COMMAND cmd)
+target_sources(lib1 PUBLIC FILE_SET src2 TYPE rule FILES lib2.c)
+assert_prop_eq(lib1 FILE_SET_TYPES "HEADERS;SOURCES;rule")
+assert_prop_eq(lib1 FILE_SETS_HEADERS "a;b;HEADERS")
+assert_prop_eq(lib1 INTERFACE_FILE_SETS_HEADERS "a;c;d;HEADERS")
+assert_prop_eq(lib1 FILE_SETS_SOURCES "src1")
+assert_prop_eq(lib1 INTERFACE_FILE_SETS_SOURCES "src1")
+assert_prop_eq(lib1 FILE_SETS_rule "src2")
+assert_prop_eq(lib1 INTERFACE_FILE_SETS_rule "src2")